1. Field of the Invention
The present invention relates to a heating and/or drying apparatus and components used therein. More particularly, the present invention is directed toward a heating and/or drying apparatus well suited for heating and/or drying solid granular or particulate material, such as aggregate comprising rocks, gravel and sand used in making asphalt concrete, for example. The apparatus according to the present invention has a novel construction which allows for the efficient and cost effective indirect transfer of heat energy from and to various parts of the apparatus.
In general, the presently preferred use contemplated for the present invention is to heat and dry aggregate used to make asphalt concrete. The aggregate usually contains a substantial amount of moisture. The amount of moisture within the aggregate can be reduced from the amount contained in the aggregate to zero moisture if desired. However, the heater and heater-condenser of the present invention may be used to heat and/or dry other materials besides the aggregate used for asphalt concrete, including other granular and/or particulate material and, with slight modifications, even liquid material
The components of the present invention considered independently of each other, as well as considered in association with each other, represent improvements over current and prior art equipment for heating and/or drying various kinds of materials and particularly aggregate material used to make asphalt concrete
2. Description of the Prior Art
One such prior art system is disclosed in the inventor's U.S. Pat. Nos. 4,245,915 entitled "Apparatus for Making Asphalt Concrete," and RE. 32,206 entitled "Process for Making Asphalt Concrete." These patents are directed, inter alia, to a system for heating aggregate in a storage bin indirectly using steam evolved during a subsequent step including heating a mixture of aggregate and binder.
There are other examples of prior art systems which dry various materials, including cement and other aggregate used to make Portland cement concrete, aggregate used to make asphalt concrete, and other solid aggregate and liquid materials. However, none of such systems are believed to provide as efficient and cost effective drying as the present invention. Moreover, the operation of the present invention results in substantially no atmospheric pollution The present invention makes use of the energy value of moisture or other liquid contained in the material to be dried, which is usually lost by evaporation in typical drying or heating systems. The present invention preferably uses substantially all of the heat generated by various components of the system in other components of the system, rather than wasting such heat as in prior art apparatus and processes.